Method for manufacturing high opacity, durable pigment
AssigneeMillennium Inorganic Chemicals, Inc.
InventorsStephen P. Kinniard, Anne Campeotto
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Abstract
The present invention relates to an improved titanium dioxide pigment that incorporate a dense silica coating and its process for manufacture. The pigment is preferably produced from a titania base from the chloride process in which the manufacturing process comprises the following steps in the order stated: (a) partial or substantial removal of salt from the oxidizer discharge; (b) addition of a dispersant; (c) milling to produce a highly dispersed, highly deagglomerated slurry, followed by dense silica surface treatment. Pigments prepared using the inventive process exhibit optics equivalent to high gloss, high opacity pigments and maintain the durability of the more conventional dense silica treated pigments.
Claims21
A process for treating titanium dioxide which comprises the following steps in the order stated:
- (a) reducing salt content of the titanium dioxide;
- (b) forming a dispersion comprising the titanium dioxide;
- (c) milling the dispersion;
- and (d) surface treating the titanium dioxide with an inorganic or organic compound.
A method of improving gloss properties of silica-coated titanium dioxide pigment comprising the steps of:
- (a) forming an admixture containing titanium dioxide;
- (b) reducing salt content of the admixture;
- (c) adding a dispersing agent to the admixture;
- (d) milling the admixture;
- (e) coating the titanium dioxide in the admixture with silica;
- and (f) recovering titanium dioxide pigment from the admixture.
In the method of treating titanium dioxide with silica, the improvement being removal of salt, followed by addition of a dispersing agent, followed by wet milling, prior to treatment with silica.
Dependencies are inferred from the claim text.